1. Field of the Invention
The invention is directed to an improved valve for a high-pressure pump of a fuel injection system for an internal combustion engine.
2. Description of the Prior Art
A high-pressure pump with such a valve of the type with which this invention is concerned is known from German Patent Disclosure DE 197 44 577 A1. This high-pressure pump has a housing in which the valve, embodied as a check valve, is disposed. The valve has a valve member in the form of a ball, which cooperates with a valve seat formed in the housing part in order to open and close a communication of a pump work chamber of the high-pressure pump with a fuel outlet. The valve seat has an at least approximately conical seat face. To achieve sure sealing of the valve seat by the valve member, the shape of the seat face in terms of roundness and its surface smoothness must be manufactured very precisely. This requires complicated machining of the seat face, for instance by means of grinding. In the known valve, the seat face is large, so that its machining requires a large tool and is time-consuming and under some circumstances leads to the removal of a large amount of material. If the housing part of the high-pressure pump is hardened, the hardened surface layer of the housing part might be removed under some circumstances, and in that case there is no longer adequate strength of the seat face, which is hence subject to severe wear. Furthermore, the flow through the known valve is not optimal, because of the major flow deflection and the attendant flow losses of the seat face.